Abstract: Trim marks of equilateral triangular shape are used to define a trim line for sheets containing machine-readable indicia. Each trim mark consists of an equilateral triangle with one corner situated along the trim line, an adjacent side extending perpendicular to that trim line, and an opposite side parallel to but spaced from the trim line. The length of the adjacent side corresponds to the acceptable severance tolerance for the trim line, so that if the sheet is cut away from the desired trim line, the visable width of the truncated triangular trim mark will equal the amount of offset. Advantageously, differently spaced pairs of such trim marks are employed on opposite sides of the desired trim line so that the separation distance between the truncated triangles provides a visual indication of the direction and possible skew of severance offset.